[Beowulf] Re: coprocessor to do "physics calculations"

[Robert G. Brown]

On Sat, 6 May 2006, SIM DOG wrote:

> Further to the discussion, AnandTech has a review of an ASUS card sporting 
> this beastie... (US$300)
>
> http://www.anandtech.com/video/showdoc.aspx?i=2751
>
> I can vaguely remember seeing some mention of AGEIA publishing the API. Just 
> Newtonian gravity calcs would be just fine by me... then if only I could 
> afford a baby GRAPE (there was some talk of a PCI-X card) :/
>
> http://astrogrape.org/

Aaaaghh.

It's alive, it's alive!
The CM-5, the CM-5...:-)

(Actually, not quite if the GRAPE-2004 is really like the CM-2 -- a SIMD
design rather than MIMD.)

There are a number of questions I would have about the architecture,
mostly about IPCs and/or other bandwidth limitations.  Saying that it is
"1 Petaflop" on what looks like a square inch of chip real estate is all
well and good, but that sounds suspiciously like a theoretical peak
speed of a (very) large number of SIMD pipelines.  At some point the
real problem will be keeping them fed with an input dataflow, will it
not?  As in I don't think that there are a lot of petabyte/sec channels
out there to keep data moving through the petaflop chain.

Of course there are things such a card could definitely be used for.
For example, I'd guess that one could load the pipes with N seeds of a
good rng and shuffle the output and generates a whole lot of
rng's/second, which would make simulationists (like myself) potentially
very happy.  I may be a bit cynical about getting a "real" petaflop
(e.g. sustained on a real dataflow) out of a single chip (and even more
so out of a card with 8 chips on it) but hey, if the price was right and
the programming was easy it might be worth it.

    rgb

>
> Cheers
> Stevo
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-- 
Robert G. Brown	                       http://www.phy.duke.edu/~rgb/
Duke University Dept. of Physics, Box 90305
Durham, N.C. 27708-0305
Phone: 1-919-660-2567  Fax: 919-660-2525     email:rgb at phy.duke.edu